The present invention relates to the extrusion of fat-containing confectionery materials, particularly chocolate and more particularly to a process for the extrusion of solid or semi-solid chocolate.
European Patent Application No. 93114251.7, the entirety of which is hereby incorporated by reference, describes a process for plastically extruding a fat-containing confectionery material which comprises feeding the fat-containing confectionery material into an extruder and applying pressure to the fat-containing confectionery material in a substantially solid or semi-solid nonpourable form upstream of a flow constriction whereby the temperature, pressure, contraction ratio and extrusion rate are such that the fat-containing confectionery material is extruded and remains in a substantially solid or semi-solid nonpourable form to produce an axially homogeneous extruded product having a cross section that is of substantially the same profile as the die exit of the extruder, which is capable of retaining its shape and which has a temporary flexibility or plasticity enabling it to be physically manipulated, cut or plastically deformed before losing its flexibility or plasticity.
In Great Britian Patent Application No. 96 06285, the entirety of which is hereby incorporated by reference, describes a process for the continuous extrusion of chocolate or a fat-containing confectionery material using a screw extruder which comprises feeding the chocolate or fat-containing confectionery material into the screw extruder and generating a pressure to force the chocolate or fat-containing confectionery material in a substantially solid or semi-solid nonpourable form upstream of a flow constriction whereby the temperature of the screw, the temperature of the barrel wall, the screw speed, pressure, contraction ratio and extrusion rate are such that the chocolate or fat-containing confectionery material is extruded in a substantially solid or semi-solid nonpourable form to produce an axially homogeneous extruded product having a cross section that is of substantially the same profile as the die exit of the extruder, which is capable of retaining its shape and which has a temporary flexibility or plasticity enabling it to be physically manipulated, cut or plastically deformed before losing its flexibility or plasticity.
The temporary flexibility of the extruded fat-containing confectionery material obtained in the process of the above-mentioned patent applications may last for up to 4 hours or more, generally from 0.1 second to 2 hours or typically from 10 seconds to 1 hour. During this period of temporary flexibility, the extruded fat-containing confectionery material may be cut cleanly, which is in the extruded material after the temporary flexibility has been lost, and to a normal set chocolate, which has to be heated slightly for cutting, otherwise it would shatter owing to its brittleness. However, the appearance of the cut extruded chocolate is not always as attractive as desired because there may be whitish streaks or blotches on both the exterior surface and on the cut surface. The streaks or blotches give a streaky pattern similar to mouldy cheese.